Rail fastening

ABSTRACT

A rail fastening comprises a resilient U-shaped clip the base of which is supported against the sleeper with the free outer ends of the clip arms engaging the rail foot. Holding down means acting against an intermediate portion of the arms stresses the clip to clamp the rail foot. The intermediate arm portions are circularly curved in a vertical plane, and the holding down means engaging the curved portions has a complementary shape. This enables greater deflection of the clip for a given clamping pressure. The outer end portions are flattened where they engage the rail foot.

United States Patent 1 1 1 3,784,098 Serafin et al. [4 ]v Jan. 8, 1974 [5 RAIL FASTENING 2,570,871 10/1951 Schulze 238/349 [75] Inventors: Marian Serafin Paris; Maurice 3,558,050 1/1971 Sonnevrlle 238/349 Decubber, Beaumont S. Oise, both of France Primary ExaminerGerald M. Forlenza [73] Assignee: Societe Anonyme de Traverses en s 4'"'"" Bcmch Beton Arme Systeme Vagneux, Paris, France 22 Filed: July 3, 1972 {571 ABSTRACT [21] Appl. N0 8,3 A rail fastening comprises a resilient U-shaped clip the base of which is supported against the sleeper with the [30] Foreign Application Priority Data free outer ends of the clip arms engaging the rail foot. Holding down means acting against an intermediate France 7128079 portion of the arms stresses the clip to clamp the rail Dec. 17, 1971 France 7145480 foot. The intermediate am portions are circularly curved in a vertical plane, and the holding down 52 }J.S.3|l. 238/349;5 238/283 means engaging the curved portions has a complemem ."l; y Shape. enables greater deflection of the le 0 care 38/349, 310, 338 for a given clamping pressure The outer end portions 5 References cued are flattened where they engage the rail foot.

UNITED STATES PATENTS 4 Claims 9 Drawing Figures 3,658,247 4/1972 Serafin et al 238/349 l/ 5/ 1 $00 I 20 0 A 50 0 1/ I lkiWz 24 2/ 157 52 J20 PATENTED 3,784,098

sum 1 BF 3 PATENTED 8 SHEET 2 BF 3 Pie-5 m mAm mAm M m R w v Y PAIENTEU 3 784 098 SHEET 3 0F 3 RAIL FASTENING This invention relates to a rail fastening, and more particularly to an improved rail clip for fixing a rail on a sleeper.

A rail fastening has been proposed which comprises a resilient rail clip substantially U-shaped in plan. The base of the clip bears against the sleeper, and the free outer end portions of the arms of the clip are engaged with the rail foot. Holding down means connected to the sleeper engage the arms of the clip at an intermediate position and deflects the arms so that the clip exerts a clamping force on the rail foot.

A disadvantage of the known rail fastenings is that it is difficult to achieve the required clamping force, and if as a result of this difficulty the rail fastening when installed exerts insufficient clamping force on the rail foot the stability of the track can be impaired.

It is an object of the present invention to provide an improved rail fastening.

It is a further object of the invention to provide a resilient rail clip in which a progressively increasing clamping force is developed by generally rotational displacement of the arms of the clip about a centre of curvature.

It is another object of the present invention to provide a resilient rail clip in which the deflection of the clip is considerably greater for a given clamping force.

The present invention provides a rail fastening comprising a resilient rail clip which is substantially U- shaped in plan and comprises a base portion engageable with a sleeper mounting and two arms extending laterally away from the base portion, the free outer end portions of which arms are engageable with the rail foot, wherein a portion of each arm intermediate its free outer end portion and the base portion of the clip is substantially circularly curved in a vertical plane for engaging holding down means of complementary shape, and each said outer end portion narrows in thickness and increases in widths from adjacent the said intermediate portion towards the outer free end.

The outer arm portions of the resilient rail clip of the invention have considerable flexibility outwardly of the curved intermediate portions, and the arms deflect by generally rotational displacement about the centre of curvature of the curved intermediate arm portions, the deflection of the clip providing a progressively increasing clamping force for securing a rail on a sleeper.

The holding down means may comprise a fixed reaction member secured to the sleeper, but preferably the holding down means comprises a sleeper bolt and a bearing member engageable with the circularly curved intermediate arm portions, and a nut on the bolt for urging the bearing member against the clip. As the'nut is tightened down the arms of the clip progressively deflect and exert a clamping force on the rail, the base portion of the clip being supported by its engagement with the sleeper mounting.

Other features and advantages of the invention will become apparent from the following description of a preferred embodiment given with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a side elevation of a rail clip in accordance with the invention;

FIG. 2 is a plan view of the rail clip of FIG. 1;

FIG. 3 is a vertical cross-sectional view of a rail fastening in accordance with the invention installed in a railway track;

FIGS. 3a, 3b and 3c respectively illustrate successive stages in the installation of the rail fastening shown in FIG. 3;

FIG. 4 is a plan view of the rail fastening shown in FIG. 3;

FIG. 5 is a perspective view of bearing means employed in the rail fastening, and

FIG. 6 is a graph relating vertical deflection of the rail clip in accordance with the invention to the clamping force developed.

Referring to FIGS. 1 and 2 of the drawings, a resilient rail clip 30 is shown. The rail clip 30 comprises a resilient spring steel member which is substantially U- shaped in plan, as seen in FIG. 2, and comprises a base portion 33 and two arms 31 and 32 extending laterally away from the base portion 33. The arms 31 and 32 each comprise a free outer end portion 31b, 32b respectively, and an intermediate portion 31a, 32a. Viewed in side elevation as in FIG. 1, the intermediate portions 31a, 32a of the arms between the free outer end portions 31b, 32b, and the base portion 33 are curved in a vertical plane, the configuration of the curved portions being substantially part of a circle having a centre at 0. Each outer end portion 31b, 32b decreases in vertical thickness h from adjacent the curved intermediate portion 31a, 32a towards the outer free end of the arm, and simultaneously increases in width I progressively from adjacent the curved intermediate portion towards the free outer end. The free outer end portions 31b, 32b each constitute a flat of substantially constant thickness and width. The width and thickness of the base portion 33 and of the intermediate arm portions 31a, 32a are constant.

As seen in FIG. 1, wherein the rail clip is shown in an unstressed condition, a plane p tangential to the lower face of the outer end portions 31b, 32b i.e., a plane containing the base of each flat forms an angle a with a plane Q containing the upper surface of the base portion 33 of the rail clip and of the inner part of each arm adjacent the base. The plane P passes above the base portion 33 of the clip and above the centre of curvature 0. Generally, the angle a will have a value of between about 3 and about 12, a suitable angle being about 10.

FIG. 3 shows the rail fastening in use to fix a rail R on a sleeper T which may be made of wood, reinforced or prestressed concrete, or metal. Only a portion of the rail R and sleeper T are shown in the Figure.

As shown, the sleeper T has a shoulder 20 which carries an insulating bearing pad 21. The foot of the rail R rests on the bearing pad 21. Adjacent the shoulder 20, the sleeper has a recess 22 which terminates in a lateral shoulder 23. A conventional sleeper bolt 50 has a nut 51 screwed onto its threaded outer end 50a. A washer 52 is placed over the bolt 50 and rests on the sleeper in the recess 22.

The lateral shoulder 23 of the sleeper T carries a support plate 24 serving as a mounting for the base portion 33 of the rail clip 30. The support plate 24 has a flange 24a which acts as a stop for the clip. The free outer end portions of the arms 31, 32 of clip 30 are engaged with.

the edge of the rail foot, a bearing plate 36 and an insulating plate 37 for insulating the rail R electrically from the rail fastening being positioned between the arm portions and the rail foot.

A bearing member 60, see also FIG. 5, is retained on the sleeper bolt 50 by the nut 51. The bearing means 60 has a central bore 60a and a bottom surface 60b having a circularly curved configurationcomplementary to curved configuration of the intermediate arm portions 31a, 32a of the clip 30 and engages the said curved intermediate portions.

The typical manner in which the rail fixing is installed will now be described with reference to FIGS. 3a, 3b and 3c.

FIG. 3a shows a preliminary stage in the installation wherein the washer 52 has been placed over the bolt 50, the rail clip 30 placed in position with the curved intermediate arm portions adjacent the bolt 50, and the bearing member 60 has been fitted onto the bolt. At this stage the rail clip rests loosely against the plate 36 on the rail foot and against the bearing plate 24.

In the next stage illustrated in FIG. 3b the nut 51 is threaded onto the bolt 50 and is screwed down. As the nut is screwed down, the bearing member 60 is forced down against the arms of the rail clip, causing the arms and particularly the outer end portions 31b, 32b progressively to deflect substantially by rotation about the centre of curvature O of the curved intermediate portions.

Tightening of the nut 51 is continued until the lower sides of the intermediate portions 31a, 32a of the arms abut firmly against the washer 52 as shown in FIG. 3c.

At the stage shown in FIG. 3a, the outer end portions 31b, 32b of the two arms of the rail clip do not exert clamping force against the rail foot. At the stage shown in FIG. 3b, an intermediate value of clamping force is exerted evenly against the rail foot by the two arms. At the final stage, shown in FIG. 3c, the maximum clamping force is exerted. The washer 52 serves as an abutment means on the sleeper which predetermines the clamping force developed by the rail clip when the nut 51 is tightened down into its final position.

FIG. 6 is a graph illustrating the progressively increasing clamping force developed by the rail clip. The ordinate shows the vertical deflection F of the rail clip expressed in millimetres, and the abscissa the clamping force S expressed in kilograms. The solid line curve represents the clamping characteristic of the rail clip in accordance with the invention, and shows the progressive increase in the clamping force developed as the clip is tightened down. The reference characters A, B, C in FIG. 6 indicate the characteristic at the successive stages of installation shown in FIGS. 30, 3b and 30, respectively.

For comparison purposes, FIG. 6 also shows in broken line the clamping characteristic of a prior art U- shaped rail clip as referred to hereinabove, and which does not incorporate the present invention. It will be seen that in the present invention the deflection of the rail clip is considerably greater for the same clamping force, which is a fundamental advantage.

A rail fastening as proposed by the present invention is simple to install and the achievement of the required clamping force is also a simple matter in that no adjustvments are required to be made during installation, the

nut 51 having merely to be tightened down until the lower sides of the rail clip come into abutment with the washer 52. By making availablev washers of different thickness, a clamping force appropriate for the conditions of the particular installation can readily be selected.

The rail fastening is also easy to dismantle, provides excellent transverse stability for the rail, allows electrical installation and is usable in connection with all types of sleepers. Although the fastening has been described in a mode which does not require the use of base plates on the sleeper, it will readily be appreciated that the rail fastening may be used in conjunction with a base plate. When the fastening is used with a base plate, the bolt 50 may extend into the sleeper as shown, or may be replaced by a shorter bolt connected to the base plate, the base plate itself being secured to the sleeper in any suitable known way.

The rail fastening according to the invention comprising the resilient rail clip may also be used as a fastening system wherein the holding down means comprises a member fixedly secured to a sleeper and having a projecting head as described, for example, in

For the purposes of illustration, a particular embodiment of the invention has been shown and described according to the best present understanding thereof. However, it will be apparent that changes and modifications in the arrangement and construction of the parts thereof may be resorted to without departing from the spirit and scope of the invention.

We claim:

1. A rail fastening comprising a resilient rail clip which is substantially U-shaped in plan and comprises a base portion engageable with a sleeper mounting and two arms extending laterally away from the base portion, the free outer end portions of which arms are engageable with the rail foot, wherein a portion of each arm intermediate its free outer end portion and the base portion of the clip is substantially circularly curved in a vertical plane for engaging holding down means of complementary shape, and each said outer end portion narrows in thickness and increases in widths from adjacent the said intermediate portion towards the outer free end, a plane extending tangentially from the lower faces of the said free outer end portions passing above the said base portion when the clip is in unstressed condition.

2. A rail fastening according to claim 1 wherein the said tangential plane makes an angle of between about 3 and about 12 with a plane containing the upper surface of the said base portion when the clip is in unstressed condition.

3. A rail fastening according to claim 2 wherein the said angle is approximately 10.

4. A rail fastening according to claim 1, wherein the holding down means comprises a sleeper bolt and a bearing member .engageable with the said circularly curved intermediate arm portions, and a nut on said bolt for urging said bearing member against said clip for stressing said clip, abutments means provided on the sleeper engaging said circularly curved intermediate portions of said arm from the side opposite said bearing means to predetermine the clamping force developed by said clip when said nut is tightened. 

1. A rail fastening comprising a resilient rail clip which is substantially U-shaped in plan and comprises a base portion engageable with a sleeper mounting and two arms extending laterally away from the base portion, the free outer end portions of which arms are engageable with the rail foot, wherein a portion of each arm intermediate its free outer end portion and the base portion of the clip is substantially circularly curved in a vertical plane for engaging holding down means of complementary shape, and each said outer end portion narrows in thickness and increases in widths from adjacent the said intermediate portion towards the outer free end, a plane extending tangentially from the lower faces of the said free outer end portions passing above the said base portion when the clip is in unstressed condition.
 2. A rail fastening according to claim 1 wherein the said tangential plane makes an angle of between about 3* and about 12* with a plane containing the upper surface of the said base portion when the clip is in unstressed condition.
 3. A rail fastening according to claim 2 wherein the said angle is approximately 10*.
 4. A rail fastening according to claim 1, wherein the holding down means comprises a sleeper bolt and a bearing member engageable with the said circularly curved intermediate arm portions, and a nut on said bolt for urging said bearing member against said clip for stressing said clip, abutments means provided on the sleeper engaging said circularly curved intermediate portions of said arm from the side opposite said bearing means to predetermine the clamping force developed by said clip when said nut is tightened. 